Low-cost Nitrogen Research Articles

Deproteinated potato wastewater as a low-cost nitrogen substrate for very high yeast biomass quantities: starting point for scaled-up applications

The aim of this research was to investigate the influence of deproteinated potato wastewater (DPW) supplemented by different initial concentrations of glucose on biomass yield, especially lipids biosynthesis and fatty acids composition. DPW is a low-cost source of nitrogen and other biogenic elements. It allowed for an efficient yeast cells growth and a very high biomass yield of Rhodotorula glutinis var. rubescens LOCKR13. A short time of incubation leads to a biomass rich in protein, which can be a source of single-cell protein. The strain was able to accumulate 46% cell dry weight (CDW) of lipids in control medium and only 18% when DPW medium were used. The maximum volumetric lipids efficiency in the DPW medium was 6.14 g L−1. Oleic (41.0–51.5%), palmitic (15.3–17.8%), and stearic acids (5.8–7.5%) dominated the entire pool of fatty acids. Theoretical calculations indicated a possibility to use the methylated esters of lipids from R. glutinis var. rubescens yeast as a biodiesel.

Effect of different nitrogen source combinations on microbial cellulose production by Pseudomonas aeruginosa in batch fermentation

Microbial cellulose (MC) is a type of polysaccharide that has high purity properties, which can be produced by different types of microorganism such as Pseudomonas, Komagataeibacter, Sarcina and Azotobacter and widely used in industrial applications. However, the main drawback in microbial cellulose production is low yield, which unable to meet the requirements of the industry. This study aims to determine the effects of different nitrogen sources combinations on microbial cellulose production by Pseudomonas aeruginosa and to maximize microbial cellulose production using the best nitrogen sources combination. To improve cellulose production, five different nitrogen sources combinations, which were yeast extract (YE) + (NH4)2SO4, YE + NH4NO3, YE + urea, YE + tryptic soy broth and YE + beef extract were added into the media with the composition of 50 g/L glucose, 3/L g KH2PO4 and 0.05 g/L MgSO4. The batch fermentation was done in incubator shaker with 150 rpm at 30°C for five days. The samples were harvested every 24 hours, centrifuged, purified and dried for microbial cellulose concentration determination. The results obtained indicated that YE and beef extract combination produced the highest microbial cellulose concentration of 1.7 g/L. To attain the second objective, optimization study was carried out by using different concentrations, which were 5 g/L, 10 g/L, 15 g/L and 20 g/L of YE and beef extract combination. An investigation using 10 g/L YE and beef extract has produced 1.7 g/L of microbial cellulose, which proved to be the potential enhancer for microbial cellulose synthesis. It is recommended that additional morphology analyses should be done to investigate the influence of fermentation conditions and low-cost nitrogen sources media components on microbial cellulose morphology and its mechanical properties. This will help to synthesize desired and reliable microbial cellulose pellicles.

Increase in an Intracellular β-Galactosidase Biosynthesis Using L. reuteri NRRL B-14171, Inducers and Alternative Low-Cost Nitrogen Sources under Submerged Cultivation

Abstract The aim of this study was to select among lactic acid bacteria (LAB) and yeast a potential β-galactosidase producer, based on bioprocess parameters. From the selected microorganism, different organic cheaper nitrogen sources (single and combined) with low cost for β-galactosidase production were evaluated. Lactobacillus reuteri B-14171 showed the highest enzymatic activity (1,286 U L−1), high productivity (28.78 U L h−1) and yield factor (82.32 U g−1), evidencing its potential for β-galactosidase production. All organic nitrogen sources tested were viable for the enzymatic production using L. reuteri B-14171. The MMRS casein (3.0 g L−1) + inactive beer yeast (3.0 g L−1) as nitrogen source increased the enzymatic activity (1269 U L−1) with 1.83 times lower production costs of culture medium when compared to MMRS-yeast extract B. The MMRS casein + inactive beer yeast has proved to be an innovative and cheaper nitrogen source for β-galactosidase production by L. reuteri B-14171.

Nitrogen sources affect productivity, desiccation tolerance and storage stability of Beauveria bassiana blastospores.

Nitrogen is a critical element in industrial fermentation media. This study investigated the influence of various nitrogen sources on blastospore production, desiccation tolerance and storage stability using two strains of the cosmopolitan insect-pathogenic fungus Beauveria bassiana. Complex organic sources of nitrogen such as soy flour, autolysed yeast and cottonseed flour induced great numbers of blastospores after 2-3days of fermentation, which also survived drying and remained viable (32-56% survival) after 9months storage at 4°C, although variations were found between strains. Nitrogen availability in the form of free amino acids directly influenced blastospore production and resistance to desiccation. Increasing glucose and nitrogen concentrations up to 120 and 30gl-1 , respectively, did not improve blastospore production but enhanced desiccation tolerance. Cell viability after drying and upon fast-rehydration was increased when ≥25g acid-hydrolysed casein per litre was supplemented in the liquid culture medium. These findings indicate that low-cost complex nitrogen compounds are suitable to enhance yeast-like growth by B. bassiana with good desiccation tolerance and therefore support its further scale-up production as a mycoinsecticide. Nitrogen is the most expensive nutrient in liquid media composition, but this study underscores the feasibility of using low-cost nitrogen compounds composed mainly of agro-industrial by-products for rapid production of desiccation-tolerant B. bassiana blastospores by liquid culture fermentation.

Economical DHA (Docosahexaenoic acid) production from Aurantiochytrium sp. KRS101 using orange peel extract and low cost nitrogen sources

The commercial production of microalgae-derived docosahexaenoic acid (DHA) has been expanding due to several advantages of algal over fish oil produced DHA. While the DHA production technology from microalgae is already economically competitive, alternatives to pure glucose and yeast extract still need to be explored to reduce the costs and increase the profits further. In the present study, orange peel waste (OPW) and various nitrogen sources were investigated as alternative nutrient sources for the economic cultivation of Aurantiochytrium sp. KRS101. The utilization of orange peel extract (OPE) supplemented with NaNO3 showed a higher DHA yield than that supplemented with NH4Cl or urea, and pH5.5 was found to be the optimum initial condition for Aurantiochytrium sp. KRS101. OPE optimized with supplemental NaNO3 (1.2g/L) resulted in a DHA yield of 0.63g/L, which was 2.5 fold greater than the yield obtained using a conventional basal medium containing a similar amount of total nitrogen and 67% greater total carbon sources. This result implied not only that the conventional use of glucose and yeast extract have lower efficiency levels during nutrient metabolism but also that the types of carbon and nutrient sources have a significant effect on the DHA yield. The addition of supplemental glucose further enhanced the biomass, fatty acid methyl esters (FAME), and DHA yields, which unveiled the high C:N ratio requirement of Aurantiochytrium sp. KRS101. These results suggest that the development and optimization of microalgae fermentation using OPE and NaNO3 is a possible route for the economical production of DHA and for the additional utilization of food waste.

Fishmeal Wastewater as A Low-Cost Nitrogen Source for γ-Polyglutamic Acid Production Using Bacillus subtilis

Fishmeal wastewater, a fishmeal processing waste, was used as culture medium to study the effect of Bacillus subtilis A3 on the production of γ-polyglutamic acid (γ-PGA). The results showed that the optimum concentration of chemical oxygen demand (CODCr) for fishmeal wastewater was 15 g/L. Moreover, addition of 30 g/L glucose and 25 g/L glutamic acid in the medium was beneficial to cell growth and production of γ-PGA. The study also showed that the high salinity of wastewater had little effect on cell growth and production of γ-PGA after dilution. Thus, the optimal medium consisted of COD 15, 30 g/L glucose, 25 g/L glutamic acid, in which the average yield of γ-PGA (25.07 ± 0.34 g/L) was obtained. The study suggested that fishmeal wastewater can be a replacement for nitrogen source for γ-PGA production, and hence it can be the cost-effective alternative in γ-PGA production. Meanwhile, the process can offset the disposal costs of the wastes.

Sensitive and selective detection of copper ions using low cost nitrogen doped carbon quantum dots as a fluorescent sensing plateform

The current study reports a facile, single step microwave assisted synthesis of nitrogen, oxygen-doped carbon quantum dots (NCQDs) with high quantum yield (~36%). The synthesized NCQDs with an average size of 4 nm demonstrate many fold increase in the intensity of photoluminescence (PL) over the undoped carbon quantum dots (CQDs). UV–Vis absorption peak exhibits a red shift of 26 nm for NCQDs with respect to pristine CQDs. The spectral shift was further confirmed by density functional theory based calculations. X-ray photoelectron spectroscopy measurements reveal the graphitic nature and significantly high nitrogen doping of NCQDs (38.2%). The NCQDs exhibited excitation dependent PL behaviour in the visible region with maximum emission peak recorded at 415 nm with optimum excitation wavelength of 340 nm. The remarkably enhanced PL properties of NCQDs have been employed as fluorescent probe for sensitive and selective sensing of Cu2+ ions. The Cu2+ quenches the fluorescence intensity of NCQDs due to its high binding affinity towards N and O containing functional groups in quantum dots. The NCQDs render a simple, reliable and sensitive detection of Cu2+ ions with limit of detection as low as 1.8 µM.

Significantly enhanced biomass production of a novel bio-therapeutic strain Lactobacillus plantarum (AS-14) by developing low cost media cultivation strategy

BackgroundProbiotic bacteria are becoming an important tool for improving human health, controlling diseases and enhancing immune responses. The availability of a cost effective cultivation conditions has profound effect on the efficiency and role of probiotic bacteria. Therefore the current study was conducted with an objective to develop a low cost growth medium for enhancing the biomass production of a bio-therapeutic bacterial strain Lactobacillus plantarum AS-14. In this work the isolation of Lactobacillus plantarum AS-14 bacterial strain was carried out from brinjal using cheese whey as a main carbon source. Moreover, the effect of four other nutritional factors besides cheese whey was investigated on the enhanced cell mass production by using response surface methodology (RSM).ResultsThe best culture medium contained 60 g/l cheese whey, 15 g/l glucose and 15 g/l corn steep liquor in addition to other minor ingredients and it resulted in maximum dry cell mass (15.41 g/l). The second-order polynomial regression model determined that the maximum cell mass production (16.02 g/l) would be obtained at temperature 40°C and pH 6.2. Comparative studies showed that cultivation using cheese whey and corn steep liquor with other components of the selected medium generated higher biomass with lower cost than that of De Man, Rogosa and Sharpe (MRS) medium under similar cultivation conditions (pH 6.2 and temperature 40°C).ConclusionIt is evident that the cell biomass of L. Plantarum AS-14 was enhanced by low cost cultivation conditions. Moreover, corn steep liquor and ammonium bisulphate were perceived as low-cost nitrogen sources in combination with other components to substitute yeast extract. Of all these factors, cheese whey, corn steep liquor, yeast extract and two operating conditions (temperature and pH) were found to be the most significant parameters. Thus the cost effective medium developed in this research might be used for large-scale commercial application where economics is quite likely important.

N-Butanol production from sucrose and sugarcane juice by engineered Clostridium tyrobutyricum overexpressing sucrose catabolism genes and adhE2

The production of n-butanol from sugarcane juice by metabolically engineered Clostridium tyrobutyricum Ct(Δack)-pscrBAK overexpressing scr operon genes (scrB, scrA, and scrK) for sucrose catabolism and an aldehyde/alcohol dehydrogenase gene (adhE2) for butanol biosynthesis was studied with corn steep liquor (CSL) as a low-cost nitrogen source. In free cell fermentation, butanol production of ∼16g/L at a yield of 0.31±0.02g/g and productivity of 0.33±0.02g/L·h was obtained from sucrose and yield of 0.24±0.02g/g and productivity of 0.30±0.01g/L·h from sugarcane juice containing sucrose, glucose and fructose. The fermentation was also studied in a fibrous bed bioreactor (FBB) operated in a repeated batch mode for 10 consecutive cycles in 10days, achieving an average butanol yield of 0.21±0.02g/g and productivity of 0.53±0.05g/L·h from sugarcane juice, demonstrating its long-term stability without applying the antibiotic selection pressure.

Pushing the Limits: 11.4-ML/D (3-mgd) Pilot Process Train at Brockton Achieves Low-Cost Nitrogen Removal to 3 mg/L TN

Pushing the Limits: 11.4-ML/D (3-mgd) Pilot Process Train at Brockton Achieves Low-Cost Nitrogen Removal to 3 mg/L TN

Production of kefiran from molasses and spent yeast cells by lactobacillus kefiranofaciens JCM 6985

Kefiran is an exopolysaccharides produced by Lactobacillus kefiranofaciens isolated from kefir grains. Kefir grains is a starter of traditional fermented milk that originated in the Caucasian Mountains in Russia. Kefiran contains glucose and galactose at a ratio 1:1. It is widely used as thickeners, stabilizers, emulsifiers and gelling agents. It also has antimicrobial and antitumor activity. The main aim of this work was to produce kefiran from low-cost carbon and nitrogen sources. Firstly, the effect of various sugars including glucose, sucrose, lactose, galactose and lactose on kefiran production were investigated. It was found that lactose gave the highest kefiran production of 283.33±15.3 mg/L followed by glucose (210±20 mg/L) and sucrose (180±5.8 mg/L). When molasses was used as a carbon source, the optimal molasses concentration was 80 g/L which gave kefiran production of 235±5.7 mg/L. The kefiran production using various low-cost nitrogen sources were investigated. Among nitrogen sources tested, spent yeast cells gave the highest kefiran production of 580±10 mg/L. Moreover, when spent yeast cells was hydrolyzed and used as nitrogen source the kefiran production was increased up to 1,286±18 mg/L. These results show that molasses and spent yeast cells can be used as low-cost nutrients for kefiran production. Kefiran is an exopolysaccharides produced by Lactobacillus kefiranofaciens isolated from kefir grains. Kefir grains is a starter of traditional fermented milk that originated in the Caucasian Mountains in Russia. Kefiran contains glucose and galactose at a ratio 1:1. It is widely used as thickeners, stabilizers, emulsifiers and gelling agents. It also has antimicrobial and antitumor activity. The main aim of this work was to produce kefiran from low-cost carbon and nitrogen sources. Firstly, the effect of various sugars including glucose, sucrose, lactose, galactose and lactose on kefiran production were investigated. It was found that lactose gave the highest kefiran production of 283.33±15.3 mg/L followed by glucose (210±20 mg/L) and sucrose (180±5.8 mg/L). When molasses was used as a carbon source, the optimal molasses concentration was 80 g/L which gave kefiran production of 235±5.7 mg/L. The kefiran production using various low-cost nitrogen sources were investigated. Among nitrogen sources tested, spent yeast cells gave the highest kefiran production of 580±10 mg/L. Moreover, when spent yeast cells was hydrolyzed and used as nitrogen source the kefiran production was increased up to 1,286±18 mg/L. These results show that molasses and spent yeast cells can be used as low-cost nutrients for kefiran production. Normal 0 false false false EN-US X-NONE TH /* Style Definitions */ table.MsoNormalTable {mso-style-name:ตารางปกต; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:8.0pt; mso-para-margin-left:0cm; line-height:107%; mso-pagination:widow-orphan; font-size:11.0pt; mso-bidi-font-size:14.0pt; font-family:Calibri,sans-serif; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;}

Modeling and optimization of Newfoundland shrimp waste hydrolysis for microbial growth using response surface methodology and artificial neural networks

The hydrolyzed protein derived from seafood waste is regarded as a premium and low-cost nitrogen source for microbial growth. In this study, optimization of enzymatic shrimp waste hydrolyzing process was investigated. The degree of hydrolysis (DH) with four processing variables including enzyme/substrate ratio (E/S), hydrolysis time, initial pH value and temperature, were monitored. The DH values were used for response surface methodology (RSM) optimization through central composite design (CCD) and for training artificial neural network (ANN) to make a process prediction. Results indicated that the optimum levels of variables are: E/S ratio at 1.64%, hydrolysis time at 3.59h, initial pH at 9 and temperature at 52.57°C. Hydrocarbon-degrading bacteria Bacillus subtilis N3-1P was cultivated using different DHs of hydrolysate. The associated growth curves were generated. The research output facilitated effective shrimp waste utilization.

A control-oriented NOx emissions model for diesel engines

A control-oriented, low computational cost nitrogen oxides emissions model for a diesel engine is presented. The model is based on zero-dimensional one-zone nitric oxide formation thermodynamics. The main inputs to the model are measured cylinder pressure, engine speed and manifold air flow rate. As only three model parameters are required, the calibration effort is minor. Instead of solving nonlinear equations to obtain the oxygen concentration from dissociation reactions, a simple estimation method used the estimated number of moles in the burned zone. The model was validated using engine data and show that the model can predict emissions with high accuracy as they vary with load, start of injection, fuel rail pressure and exhaust gas recirculation rate. As there are few, relatively simple algorithms involved, this model can easily be implemented online. It also has potential to be used in the control of both exhaust after-treatment and the engine combustion process.

Cheese whey: A cost-effective alternative for hyaluronic acid production by Streptococcus zooepidemicus

This study focuses on the optimisation of cheese whey formulated media for the production of hyaluronic acid (HA) by Streptococcus zooepidemicus. Culture media containing whey (W; 2.1g/L) or whey hydrolysate (WH; 2.4g/L) gave the highest HA productions. Both W and WH produced high yields on protein consumed, suggesting cheese whey is a good nitrogen source for S. zooepidemicus production of HA. Polysaccharide concentrations of 4.0g/L and 3.2g/L were produced in W and WH in a further scale-up to 5L bioreactors, confirming the suitability of the low-cost nitrogen source. Cheese whey culture media provided high molecular weight (>3000kDa) HA products. This study revealed replacing the commercial peptone by the low-cost alternative could reduce HA production costs by up to a 70% compared to synthetic media.

Continuous enhancement of iturin A production by Bacillus subtilis with a stepwise two-stage glucose feeding strategy.

BackgroundThe lipopeptide antibiotic iturin A is an attractive biopesticide with the potential to replace chemical-based pesticides for controlling plant pathogens. However, its industrial fermentation has not been realized due to the high production costs and low product concentrations. This study aims to enhance iturin A production by performing a novel fermentation process with effective glucose feeding control using rapeseed meal as a low-cost nitrogen source.ResultsWe demonstrated that continuous and significant enhancement of iturin A production could be achieved by a novel two-stage glucose-feeding strategy with a stepwise decrease in feeding rate. Using this strategy, the ratio of spores to total cells could be maintained at a desirable/stable level of 0.80–0.86, and the reducing sugar concentration could be controlled at a low level of 2–3 g/L so that optimal substrate balance could be maintained throughout the feeding phase. As a result, the maximum iturin A concentration reached 1.12 g/L, which was two-fold higher than that of batch culture.ConclusionsThis is the first report which uses control of the glucose supply to improve iturin A production by fed-batch fermentation and identifies some important factors necessary to realize industrial iturin A production. This approach may also enhance the production of other useful secondary metabolites by Bacillus subtilis.

Enhanced l-lysine production from pretreated beet molasses by engineered Escherichia coli in fed-batch fermentation

Faster sugar consumption rate and low-cost nitrogen source are required for the chemical biosynthesis using molasses. Five pretreatment methods were applied to beet molasses prior to fermentation through engineered Escherichia coli, respectively, and corn steep liquid was used as an organic nitrogen source to replace expensive yeast extract. Furthermore, the effects of different feeding strategy in fed-batch fermentation on L-lysine production were investigated. The experimental results showed that combined tricalcium phosphate, sulfuric acid, and activated carbon pretreatment method (TPSA) pretreatment could improve the sugar consumption rate most greatly, and the initial total sugar concentration of 35 g/L from TPSA-pretreated beet molasses gave the best results with respect to L-lysine production, dry cell weight concentration, and L-lysine yield in batch fermentation. Moreover, a mixture of low-cost corn steep liquid and yeast extract containing equal amount of nitrogen could be used as the organic nitrogen source for effective L-lysine fermentation, and constant speed feeding strategy of TPSA-pretreated beet molasses promoted L-lysine production by engineered E. coli. The TPSA-pretreated beet molasses had a sugar consumption rate of 1.75 g/(L h), and a L-lysine yield of 27.81% was achieved, compared with the theoretical yield of 62% by glucose. It was clarified that the pretreatment significantly enhanced the conversion of sugars in beet molasses to L-lysine.

Isolation, characterization and optimization of photo-hydrogen production conditions by newly isolated Rhodobacter sphaeroides KKU-PS5

Abstract A purple non-sulfur (PNS) photosynthetic bacterium was isolated from an upflow anaerobic sludge blanket (UASB) bioreactor for methane production and was identified as Rhodobacter sphaeroides KKU-PS5 (GenBank Accession no. KC481702) by 16s rRNA gene sequence analysis. Strain KKU-PS5 could utilize glucose, xylose, fructose, arabinose, malate, succinate, acetate, butyrate, lactate and D-mannitol for growth and hydrogen production. Malate was a preferred carbon source while glutamate and Aji-L (waste from the process of crystallizing monosodium glutamate) were the preferred nitrogen sources. The ability to utilize Aji-L as a low-cost nitrogen supplement for photo-biohydrogen production by the strain KKU-PS5 is considered as its desirable characteristic. The threshold substrate concentration of malate was 30 mmol/L. The optimum conditions for hydrogen production from malate were an initial pH of 7.0, FeSO4 concentration of 4 mg/L, temperature of 30 °C and light intensity of 6 klux. Under the optimum conditions, the maximum hydrogen production, the hydrogen yield (HY) and the hydrogen production rate (HPR) of 1330 mL-H2/L, 3.80 mol-H2/mol-malate, and 11.08 mL-H2/L h, respectively, were achieved. Hydrogen production under a dark/light cycle led to a decreased HY and HPR in comparison to continuous illumination.

Use of Hydro-lysates from Thunnus Tonggol Viscera as a Peptone for Listeria monocytogenes Gowth Media

The objective of this study was to produce fish peptone from tuna (Thunnus tonggol) viscera, by Alcalase. Response Surface Methodology (RSM) was employed for optimizing the temperature and pH. Hydrolysis was done in different tempratures (50-65˚C) , pH (8-8. 5) and selected 13 treatments. Samples with higher value of protein were used instead of the standard peptones which applied in commercial media for Listeria monocytogenes. Based on the three-dimensional graphs, the optimum condition for temperature and pH were determined to be 50˚C and 8. 5 respectively. The results showed that the highest (76. 89 g/l) and the lowest (38. 54 g/l) rates of protein content were related to pH 8 at 57˚C and pH 8 at 50˚C. Maximum bacterial growth rate was related to pH 8 at 65˚C. Results also showed that tuna (Thunnus tonggol) viscera can be used as low cost nitrogen sources for Listeria monocytogenes growth media.

Dried Spent Yeast and Its Hydrolysate as Nitrogen Supplements for Single Batch and Repeated-Batch Ethanol Fermentation from Sweet Sorghum Juice

Dried spent yeast (DSY) and its hydrolysate (DSYH) were used as low-cost nitrogen supplements to improve ethanol production from sweet sorghum juice by Saccharomyces cerevisiae NP01 under very high gravity (VHG) fermentation (280 g·L−1 of total sugar) conditions. The supplemented DSY and DSYH concentrations were 11, 16 and 21 g·L−1, corresponding to a yeast extract nitrogen content of 6, 9 and 12 g·L−1, respectively. The initial yeast cell concentration for ethanol fermentation was approximately 5 × 107 cells·mL−1. The fermentation was carried out in single batch mode at 30 °C in 1-L air-locked bottles with an agitation rate of 100 rpm. Ethanol production from the juice with and without yeast extract (9 g·L−1) was also performed as control treatments. The results showed that DSY at 21 g·L−1gave the highest ethanol concentration (PE, 107 g·L−1) and yield (Yp/s, 0.47 g·g−1). The use of DSYH at the same DSY concentration improved ethanol productivity (Qp), but not PE and Yp/s. The ethanol production efficiencies of the juice under DSY and DSYH supplementations were markedly higher than those without nutrient supplementation. However, the PE and Qp values of the juice containing 21 g·L−1 of DSY was approximately 7 g·L−1 and 0.62 g·L−1·h−1 lower than those under the presence of yeast extract (9 g·L−1), respectively. At the end of the single batch fermentation under the optimum DSY concentration, the sugar consumption was approximately 80%. Therefore in the repeated-batch fermentation, the initial total sugar was reduced to 240 g·L−1. The results showed that the system could be carried out at least 20 successive batches with the average PE, Yp/s and Qp of 95 g·L−1, 0.46 g·g−1 and 1.45 g·L−1·h−1, respectively.

Bacterial Cellulose from Simple and Low Cost Production Media by Gluconacetobacter xylinus

Bacterial cellulose pellicles were produced by Gluconacetobacter xylinus using non conventional low-cost carbon sources, such as glycerol remaining from biodiesel production and grape bagasse, a residue of wine production. The carbon sources assayed showed their suitability for microbial cellulose production, with relatively high production values such as 10.0 g/l for the culture medium with glycerol from biodiesel as carbon source and corn steep liquor as nitrogen source; and 8.0 g/l for the culture medium containing grape bagasse and corn steep liquor. Glucose, commercial glycerol and cane molasses were also assayed as carbon sources for comparison. The bacterial celluloses produced were characterized by means of scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and thermogravimetric analysis. Morphological analysis showed that bacterial cellulose microfibrils produced from the non-conventional media used were several micrometers long and had rectangular cross-sections with widths and thicknesses in the range of 35–70 and 13–24 nm, respectively. X-ray patterns showed crystallinity levels in the range of 74–79 % (area method), whereas both X-ray patterns and infrared spectroscopy evidenced the presence of peaks characteristic of Cellulose I polymorph. Besides thermal properties were similar to those found for the pellicle obtained from glucose. The study performed showed the suitability of using wine residues or glycerol remaining from increasing biodiesel production as cheap carbon sources for production of bacterial cellulose microfibrils, with similar characteristics as those obtained by use of more expensive carbon sources such as glucose or commercial glycerol. On the other hand, the low cost nitrogen sources used (corn steep liquor or diammonium phosphate) also contributed to the economy of the bioprocess.